Design, synthesis and anticancer properties of IsoCombretaQuinolines as potent tubulin assembly inhibitors

The synthesis and evaluation of a new series of IsoCombretaQuinolines (IsoCoQuines) 2 with a 2-substituted-quinoline in place of the 3,4,5-trimethoxyphenyl ring present in isoCA-4 and CA-4 are described. Most of these compounds displayed a potent cytotoxic activity (IC₅₀ < 10 nM) against a panel of five human Cancer cell lines and inhibited tubulin assembly at a micromolar level. The most potent analogue 2b, having a 3-hydroxy-4-methoxyphenyl as B-ring, led to cell cycle arrest in G2/M phase. Docking studies indicate that 2b showed a binding mode comparable to those previously observed with quinazoline analogous (IsoCoQ) and with isoCA-4 at the colchicine binding site of tubulin.